Method of making molds



J. F. KELLY El'AL METHOD OF MAKING MOLDS Original lFiled Sept. 18, 1939wN/n//Wf/m/fM//r/l//ll//l/l/l//l/m .J x .w NM 3 @m ,J 666..,........ W v.v.. Y F /m n n. l 2 4 1\\ O uw m w KV N o 2 f N A ..9 Tl.

Patented Der; '3, '194e i UNiTE-D srA'rssi-rA'rur oFFlc METHOD 0F ma'LIOLDSV John n.` 'Kelly and wlmm J. muy, mm, A W. va., asslgnors toKelly Foundry and Mag chine Gompanblkins, W. Va.

Original application September 18. 1939, Serial No. 295,551, now PatentNo. 2,326,730, dated August 10, 1943. Divided and this application YJune 12, 1943, Serial No. 490,580 x lI This application is a division ofour co-pendihg application Serial Number 295.551 flied September 18,1939, which matured as Patent No. 2,326,- '730, dated August;` 10, 1943,for Mold andmethod of making same. The present application has to dowith the process involved in said application.

This invention relates to bi-metallic constructions wherein two metalsare united together and to the process of making such constructions.More specifically, the invention relates to glass molds and to themethod of making as well as the method of using suchmolds.

The primary object of this invention is to pro- 1`Claim. (CL 76-107) Ifor several different shapes of articles. As Yan example of this latterfeature, we point out that afterl using the mold for producing articlesof certain dimensions that the mold may be machined vto a new shape'thus enabling articles of other dimensions to be produced. f

'I'he prior art has r Y of a glass mold must be free from oxidation, and

both cast iron as well as pure nickel have been.

duce a low cost bi-metallic construction having A one surface thereofsuited for glass molding work and in which the two parts of theconstruction are so fused together as to enable eillcient transmissionof heat away from` the cavity to the other surfaces of the mold.

Other objects of this invention' will appear as this descriptionproceeds.

In carrying out the above object, we use an inner layer of a chilled,corrosion resistant cast iron which denes the cavity of said mold. 'I'hematerial which we employ in the construction of the glass formingimplements hereof, which comprise a. glass" mold and a plunger,ispreferably a nickel-iron alloy having a nickel content well above 20%although this particular alloy is not essential and our invention may becarried out with various heat resistant materials. Durproposed asmaterials for such molds. With such limitations as cost, a nickel glassmold cannot be made thick enough so that its outer surface has enougharea to effectively dissipate the heat. Ithasbeenproposedtocastaringofironaround such a nickel insert. however, inabsence of fusion between the cast iron and the nickel insert therewould be considerable resistance to heat iiow at the junction of thenickel and iron. l The present invention contemplates a glass mold inwhich the innerstainlesspartisfusedtotheouterlayer u have found it to bea very marked improvement of cast iron, which outer layer is made verythick soitwillhavebothalargeexternalsurfacearea and a large heatdissipating area. Such a glass mold characterizes the present invention,and we over glass molds known to the prior art.

A proposal that has been made by inventors of the prior art is to weld,by ordinary welding methods, a non-oxidizable lcoating upon an 9ooxidizable metal but that proposal differs consid- 1600 F. in anon-oxidizing medium, transferred.

to a foundry mold in such a manner .that its con'- tact with the air isvery brief, and then coated 4 Vart suchras the prior molds'recitedabove, it is with a very thick layer of cast iron bythe step of castingordinary cast iron about theisame. With our `process, the ordinarycastironfuses with the nickel-'iron 'alloypart and thereby createsmoldthan whichwas 'cast in a'sand mold.. v When 'irmfis castfagainstachill, the

a very'emcient heat'ilow path from the to the outer surfaces of the`Thep'resent invention-v satisfies requireouter surfaces ,of thev mold.Moreover, f themew @am f I v louniformanddense.- Howevergincatinaglassheat dissipation from the molding cavity to mold siichasinventors of:the prior art.' 1t'is 1m .with usual casting methods to.

mold is'inexpensiveto manufacture, can b e man;

' ufactured withoutappreciable'probabilityof uri-- reliable operation,and may are subject to the great disadvantage er being inicompletelyVwelded, the disadvantage of having air pocketsv at the joints,and theycan ordinarily j be built only when simple :cavities are used. Ac-

c ol'i'llngly, it is apparent that when the mold of our invention iscompared withmolds of the prior seen thatwehave made considerableimprove cost, and surface ch aractex'isti cs.

chilled cast iron makes'a muchbetter glass offthe `chill mold conductsheat Y Yaway-"frolnfv the hot iron causing' the latter to -coolrapldmthe resultant casting set vthe center working section of tbecasting'.asdmseasdesired.

that'the surface a chill and since this becomes very dense throughout.With our process, an outer layer may be cast onto as well as insert isrelatively thin it fused to this insert without destroying the nighdegree of density of the insert. Hence, we can produce a glass moldwhich is very dense in its central working section. To avoid crackingthe thin inner part or insert, it is desirable to use metals forboth'the inner and outer layers which have similar coemcients of thermalexpansion as well as similar melting points.

Inthe drawing:

Figure 1 illustrates a machine for manufacturing glass articles andincludes a'glass producing machine, a glass mold. a plunger, and avalve.

' Figure il is a top view of the mold of Figure 1 without the plunger,valve, or glass producing machine being shown.

Figure 3 illustrates apparatus that may be employed in carrying out theprocess which is claimed to be our invention.

Figure 4 is a sectional view of a chill mold that 4 may be used forcasting nickel-iron alloy inserts. V

In Figure 1, an outer grey or white cast iron sleeve I0 surroundsand isfused to the inner nickel-iron alloy part II. While this specificationspecifies that cast iron is used for layer III, we recognize that anygood heat conductor-such as copper or aluminum may be used in forminglayer III without departing from the very broadordinary drinking glass.The surface I3 of insert I I is machined to such a shape.

A plunger is often used in glass manufacturing machinery and a suitableplunger is shown in Figure 1 directly above the mold cavity Isa. Thisplunger has a cast iron 'section I4 with an outer layer I5 ofnickel-iron alloy cast iron fused thereto. 'I'he surf-ace of layer I5conforms to the shape of the inner side of the glass articles to beproduced, for example, it may conform to .the inner surface of saiddrinking glass. In addition Ito the .mold and plunger, most glassmanufac- .turing equipment of the type being considered employs a valvewhich in Figure 1 is shown directly below the mold cavity Isa. Thisvalve has a white or grey cast iron base I2 with a nickel-iron alloycoating I3 fused thereto.

The method of manufacturing glass molds such asvthose shown in Figure 1will now lbe described,

reference being made particularly to-Figure :iL

although like parts von all figures are represented by like numbers. i o

An alloy insert I-I, of suitable stainless metal such as the alloysdescribed elsewhere in this disclosure, is ilrst cast in` a cylindricalchill `mold having thick chill walls. The cavity I3a may be cast intothe insert originally or it may be machined into the insert immediatelyafter the casting step is completed. Preferably, however, the cavity Isais machined into the mold asthe last step in the production of the mold.

After being cast, the outer :surfacexwall Aof 'in.

sert II is thoroughly cleaned, preferably by ma- 4 the process. Insteadof coating the part II with lampblack, it may be coated with copper byelectroplating. The insert I l is then placed in chamber 22 whichchamber is only slightly larger than the insert II. This chamber 'mayhave a charcoal lining but this is not necessary. A removable cement lid23 is placed on-chamber 22. 'I'he .chamber 22 is then placed in a gasfurnace 34 of any suitable type but preferably a furnace in which alarge number of jets 2| emerge tangentially from the inner surface ofthe furnace 34. The Jets 2| are so arranged that a smooth band of flamesexist, for-a distance of about three inches from the inner wall offurnace 34. 'Ihe overall diameter of the furnace is lthree to ve feet.'I'he Jets all face in the same angular direction and propel the flamesaround the inner wall of the furnace. The hot gases pass out theopeningsua respectively located at the top and bottom of the furnace 3l.As a result, the llames and hot gases act on al1 sides of chamber 22forcing heat4 evenly into this small chamber to such an extent thatinsert II is evenly heated to 'a temperature well above red heat andpreferably to a temperature above 1600 F.

When suillcientv time has elapsed for heat to fully penetrate the insertII to raise the same to say 1600 F. yorslightly hotter, the entire smallchamber 22 is removed to position 22a where it ls adjacent the foundrymold 35. If the insert II were transferred to position IIa without usingthe chamber 22, the insert would oxidize slightly and impair theresultant glass mold. When at position 22a, the lid 23 is removed andthe insert IIa removed and quickly brushed so as to remove the carbonwhich was deposited or smoked on the insert previously. In event themodified process is used wherein the insert is coated with copper it isnot necessary to remove the coating. After being brushed, the insert I Iis placed in the foundry mold 35 at position IIb. The foundry mold' 35is then quickly dry sand core material is used to remove the hot gasesfrom the molding chamber within 35. It is understood that the insert I Iis substantially at 1600 F. at the time the outer layer I0 is castthereon by the process Just outlined.

Since the nickel-iron alloy part II is the only partof our mold thatcomes into contact with the hot glass, it is not absolutelyessentialthat foundry mold 35 have chill walls although it is desirable that itdoes. Ordinary sand walls will A be satisfactory. The nickel-alloy partII has excellent heat and corrosion resistance yet a melting mintapproximately the same as ordinary cast iron.v All of the iron alloycompositions described indetail in this disclosure have melting pointsbetween 1990 F. and 2280 F. and Vwhen such alloys are used in makinginsert I I, it `is necessary to'heat the insert to only about 1600 F. infurnace 34. The insert II is further heated on its outer surface by thehot cast iron coming into the foundry mold 35 and the' temperature ofthe insert is thereby raised to the fusion point. Hence, the cast ironfrom ladle 3| thoroughly fuses with insert II and a wide band of alloybetween the two is formed in the mold. This wide band is illustrated inFigure 1 and specifically designated by reference number 36. Withordinary welding methods alloying between the parts of the resistantmold would be restricted to a very narrow band and be quite inferior tothe junction of our invention wherein very intimate association of theparts I and I I is eiected. If an insert I I is used which has a meltingpoint higher than 2280 F., it is desirable to heat the insert II to atemperature well above 1600 F. before pouring iron from ladle 3|. On theother hand, if an insert II should be used that has a very low meltingpoint, perhaps little or no preliminary heating of it would benecessary. l

We also recognize that the glass mold of Figure 1 can be manufactured bya modified process now to be described. The outer part I0 is first castin the foundry mold 35 with, a dry sand core at IIb instead of thenickel-iron alloy insert. The outer part I0 is then removed from themol-d and the cavity which was produced by the'core IIb machined so asto clean the innersurface thereof. The outer part I0 is then placed-inthe furnace 34 and heated almost to its fusion temperature at which timeit is used as a mold and the nickel-alloy inner part I I poured directlyinto the cavity of the part I0. This may be done while part I0 is stillin the furnace 22 or it may be done after the part I0 is removed fromfurnace 22, but in any event it must be done while outerk part III ishot. The cavity I9 is then machined into the inner part II.

As shown'in Figure 1, both the plunger and the valve may be ofbimetallic construction. Either may be produced by the processes recitedabove. For example, the nickel-iron alloy piece I may be machined toshape from the cast state, heated to 1600 F., transferred to a mold in asuitable small chamber similar to chamber 22, and cast iron I4 pouredthereinto. It is also apparent that part Il may be cast first and partlI5 later.

While the nickel-iron alloys contemplated by this invention arerelatively stainless it has been found that after atime, in fact arather long time as compared to ordinary glass molds, their surfacesbecome less efficient than the surfaces of new molds. When this occurs,the mold surface may-be machined to new dimensions I1, and the plungerI5 may be machined to new dimensions I8. Further pouring of glass from'I5 will produce glasses having a thick wall instead of a thin wall asoriginally.

As heretofore stated, the broadest' aspects of this invention are notlimited to any particular material for either the insert' I I or theouter partA III. Suitable materials are listed below. The preferredcomposition for the insert Il is:

Preferred Minimum, Maximum,

Element percentage per cent .per een Carbon 3. 00 2. 25 3. Silicon2.00 1. 00 3. Mangan 0. 70l 0. 50 l. Chromium 3. 50 0. 00 '6. Nickel.29.00 20. 00 50. Molybdenum 1. 00 0. 00 2.

Usual impurities, balance iron.

The above alloy is suitable for use on vthe surface of the plungeras'well as for use in insert II. Another alloy suitable for either theinsert II or the plunger surface I5 is:

asa resultthe iunction would Balance is iron with usual impurities.

Another type of iron which may be used for either the insert II or theplunger surface I5 is:

Preferred Minimum, Maximum,

Element percentage per nt per cent Total carbon 3 70 3.00 4.00Silicon---" 2. 10 1. 00 3. Il) .Nickel l. 00 0. 00 2.00 Chromium.- 0. l00. 00 LII) Molybdenum 0. 90 0. 00 1. 00

Balance iron with usual impurities.

Thev above types of alloys as well as the ones listed below are allmelted in a cupola according to standard foundry practice for thesegeneral types of irons and poured into permanent molds having thickmetal chill walls.

The cast `iron that is poured into the gating 30a of Figure 3, to formthe outer layer III of Fieure 1, and the iron used in making the sectionI4 illustrated also in Figure 1, has a preferred composition of totalcarbon 3.5%; and/silicon 2.20%. The carbon content Works well betweenthe limits of 3.00 to 4.00% and the silicon may vary within the limitsof 1.50% and 2.75%. The balance isiron with usual impurities. Thislatter iron may be used for the insert Il and surface I5 but it is notas good/as the other alloys for that use. It is quite satisfactory forthe insert Il and in fact a mold constructed according to our process,even with this type of iron for the insert, is superior to prior artmolds ess enables fus to thoroughly chill such a cast iron and therebygreatly improve its qualities above the qualities that would be obtainedif such ordinary cast iron were used in any ordinary glass mold vof theprior art.

`carbon is very eillciently changed to ljacent our molding surface I9.

` its outersurface against a Iwall layer of the liner.

We claim: 'I'he method of making a steel liner'in a glass mold whichconsists in the steps of casting a liner of heat-resistant noncorrosiveferrous alloy 'with thick chill wall to produce a liner the outer walllayer of which is chilled, cleaning the perimetral surface of the liner,heating the liner, casting' a mass of cast iron around the perimetralsurface of the heated liner to fuse the chilled portion of the liner andthe exterior mass, and machining out the interior ofthe liner to providea thin glass forming m`old surface in the outer portion of -the chilledJOHN F. KELLY. A WILLIAM J. KELLY.

inasmuch as our procthe chill mold precipi-V

